1. Field of the Invention
The present invention relates to a system for transferring loads across a joint between cast-in-place slabs, more particularly at a crossover point of a joint between cast-in-place slabs. The system for transferring loads at a crossover point comprises at least one dowel plate and means for limiting the relative movements of the dowel plate towards the joint elements along three orthogonal directions.
2. The Prior Art
Systems for transferring loads across a joint between cast-in-place slabs are disclosed for example in EP1034340, EP1584746, EP1985759, EP1867783, WO2008/064436. Each slab is provided along its edges with a metal profile working with the profile extending along an edge of an adjacent slab. At the corner of the slab defined between a first edge with a first metal profile and a second edge with a second metal profile, the said first and second profiles are welded together, so as to increase the protection of the corner. (see for example FIG. 7 of EP1389648).
However, at the crossover point of the four cast-in-place slabs, there is no means for transferring load between two cast-in-place slabs, especially a means for transferring load between two cast-in-place slabs having no direct joint there between formed by metal profiles located in front the one to the other.
When vehicles are passing over one crossover point, a good load transfer is not achieved at the crossover points, meaning that formation of cracks at the corners of the slabs adjacent to the crossover point will appear, such cracks then forming the start of larger damages within the slabs.
The correct welding together of the two ends of metal profiles is not easy as a correct angle has to be respected, as the profiles has to be cut at the correct length for having the ends to be welded together adjacent the one to the other, and as the free place for the welding operation is limited.
In order to prevent the welding together of ends of profiles intended to form a corner of a cast-in-place slab, it has been proposed to form crossover point system comprising four angle joint elements, whereby each of said angle joint element comprises a portion of a first profile, a portion of a second profile, and a welding line connecting an end of the portion of the first profile to an end of the profile of the second profile. Said profile portions welded together define a right angle there between.
The said portions of the profiles welded together are each provided with a U shaped part defining a channel. The channel of a portion of a profile of one angle joint element extends in front of a channel of a portion of a profile of another angle joint element.
Each portion of the profiles of each joint angle is then welded with a profile adapted to extend along an edge of a cast-in-place slab, whereby along each edge of a slab, an elongated channel is formed extending from, one corner from a slab to another corner of the considered slab. The welding operation is complicated as requiring the welding the U shaped part of a portion of an angle joint element with the U shaped part of the adjacent profile.
After the welding is operated, a band is placed in the longitudinal passage formed by the channels of profiles located in front the one to the other. In said passage, longitudinal metal bands (having a constant width all along their length) are placed so as to form means for transferring load between the profiles located between the edges of two adjacent cast-in-place slabs, i.e. from one profile to the other profile.
The bands have a length adapted for not crossing the crossover point between angle join elements.
This system is used for transferring a load from one profile attached to one cast in-place slab to another profile attached to another cast-in-place slab, but not for transferring a load across the adjacent corners of the four adjacent slabs.
Furthermore, it has been observed that cast-in-place slabs provided with angle joint elements formed by profile portions welded together at right angles had some cracks due to retraction phenomena of the concrete cast within the slab spaces defined between the various joint profiles.
The present invention seeks to provide a simple system enabling an easy load transfer at the corners of three or four adjacent slabs, enabling an effective load transfer across the crossover point. Moreover, in preferred embodiments of the invention, the system of the invention enables a better resistance to the appearance of cracks at the corner ends of the cast-in-place slabs.
Another goal of the system of the invention is to provide a system for efficiently transferring loads at a crossover point of a joint between cast-in-place slabs.